Apparatus for producing uniform solid spheres of hydrogen

An apparatus has been constructed which produces uniform spheres of solid hydrogen for experiments testing the feasibility of using the solid hydrogen pellets for refueling fusion reactors. Two versions of the apparatus were developed, one which produced 70‐μm‐diam pellets at the rate of 105/sec and another which produced 210‐μm pellets at the rate of 2.6×104/sec. The first step in the pellet production is to liquefy the hydrogen by flowing it through a liquid‐helium‐cooled heat exchanger. Then, a liquid hydrogen jet is formed by flowing the hydrogen through a nozzle. The jet is broken up into uniform drops by an acoustical excitation. The drops are frozen by evaporation in a pressure less than the triple point pressure of hydrogen. Finally, the drops are injected into vacuum for the experiments.